"I'm not sorry" => (전혀 / 하나도 / 조금도) 미안하지 않아 / 안 미안해 / 미안한 마음(이) 들지 않아. - (전혀 / 하나도 / 조금도): (not) in the least. - 미안한 마음이 들지 않아: No sorry feelings arise in me.

Hi :) I'm Kwangmin~ nice to meet you~

This has many expressions according to the context. 1. 미안하지 않아요.(not apologizing to someone for something that you have done.) 죄송하지 않아요.(honorific) 2. 후회하지 않아요.(to express that you don't regret something.) 3. 유감스럽지 않아요.(to express that you are not sad when you hear sad or unpleasant news.)